The present invention relates to a drive for automatic lance-changing devices, especially for lances to be coupled and fastened to a vertically movable lance carriage in a top-blowing steel making processes, where the materials required for the blowing, and in some cases also for cooling, are fed to a coupling head on the lance carriage and transferred into the lance top part at the coupling point between the coupling head and said lance top part. Such lance-changing devices have on each of the two sides of the vertical axis of the lance-carriage coupling head a lance-receiving hook pivotable about a horizontal axis of rotation and carried by the lance carriage, means for the synchronous vertical displacement of these hooks relative to the carriage and to the coupling head, means which, during this displacement of the hooks, cause the hooks to pivot about their said axis of rotation, and means for measuring the load acting on each hook, this load being a function of the force with which the lance top part is pressed against said coupling head by the hooks.
An automatic lance-changing device of the abovementioned type is described in detail in the U.S. Pat. No. 4,893,791, which is incorporated herein by reference. In this prior art lance-changing device, the drive, that is to say the operation of the coupling mechanism for grasping the lance top part and pressing this against said coupling head, is obtained, on the one hand, by means of a drive motor with a following reduction gear and, on the other hand, by means of a separate lifting-spindle system for each of two hooks. Although this automatic lance-changing device works well for its intended purposes, it has various practical disadvantages. Because the two lifting-spindle systems must be loaded synchronously, the reduction gear must have two outputs, and therefore an "off-the-shelf" gear cannot be used for this gear; rather a correspondingly more expensive custom gear must be used.
Furthermore, the separate arrangement of the gear and lifting-spindle system of this prior art device makes its construction both relatively expensive and space-consuming. Finally, the arrangement of the motor and gear in the prior art device is also unfavorable because it restricts the possibilities of the three-dimensional layout of the lines feeding said blowing materials to the coupling head (see, for example, in FIG. 1 of the U.S. Pat. No. 4,893,791, the line 6 which necessarily has to be arranged so as to extend underneath the lance-carriage plate 10).